Continuous Glucose Monitoring Metrics in Women with Type 2 Diabetes in Pregnancy: The TIMELY Observational Cohort...

Continuous glucose monitoring (CGM) is increasingly used in pregnancy, but data on its use in women with type 2 diabetes are limited.

To describe CGM metrics in pregnant women with type 2 diabetes and assess their association with neonatal outcomes.

We conducted a prospective, observational cohort study of women with type 2 diabetes, enrolled before 26 weeks of gestation. Participants wore a Dexcom G6 sensor for at least 10 days per trimester. Maternal characteristics and pregnancy outcomes were collected.

We recruited 50 women with type 2 diabetes in pregnancy from three diabetes in pregnancy clinics. Women were enrolled at a mean of 16 weeks of gestation, 83% were non-European ethnicity and 74% wore the CGM >80% of the time from enrollment. Participants spent a mean of 73.0% of time in the pregnancy range (TIRp) (3.5-7.8 mmol/L), 25.6% above range (TARp), 1.5% below range, with a mean glucose of 6.8 (1.0) mmol/L across pregnancy. Lower TIRp, higher TARp, and higher mean glucose were significantly associated with large-for-gestational-age (LGA) infants. Mean glucose was significantly higher in those with an LGA infant from 12 weeks onward. LGA was significantly more frequent in those who spent ≤70% TIRp than in those who spent >70% TIRp (46.7% vs. 10.3%; P = 0.02). TARp >30% was significantly associated with the composite neonatal outcome. More than 20% TARp overnight was significantly associated with LGA. A 5% improvement in TIRp reduced LGA by 28% (odds ratio 0.72 [0.54, 0.90; P = 0.009]). Diabetes distress at enrollment was associated with a significantly lower TIRp and higher mean glucose throughout pregnancy.

Several glycemic metrics, including TIRp and mean glucose, were associated with LGA. Higher glucose levels from 12 weeks onward were seen in mothers of LGA infants. Early pregnancy or preconception glucose optimization may be necessary to improve outcomes.